Re: [boost] Boost Evolution

Subject: Re: [boost] Boost Evolution
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-10-11 06:42:57

vicente.botet wrote:
> From: "Stewart, Robert" <Robert.Stewart_at_[hidden]>
> > vicente.botet wrote:
> >> From: "Robert Ramey" <ramey_at_[hidden]>
> >>
> >> > I'm somewhat confused about "detail".  If it's an
> >> > implemenation detail of a particular library it should be
> >> > in that library.
> >>
> >> +1, and I this that the name space should be prefixed by the
> >> name of the library as ratio::ratio_detail.
> >
> > Why not boost::ratio::detail?  Why part namespace, part prefix?
> >
> > When I raised the issue with Boost.Ratio, the problem was
> > you used boost::detail and I was concerned with cluttering
> > that widely used namespace.  If you had a boost::ratio
> > namespace, then boost::ratio::detail would work.  However,
> > because your class template is boost::ratio<>, you can't have
> > a boost::ratio namespace.  You could have one named
> > boost::ratios, so boost::ratios::detail would work.
> >
> > Is that a reasonable pattern to require for
> > future/refactored libraries?
>
> There could be a conflict with other detail namespaces if the
> user adds
>
> using namespace boost;
> using namespace boost::ratios;

Of course there could.  This can go on ad infinitum, but we do
see value in namespaces.  In that particular case, one can still
write boost::detail or boost::ratios::details or ratios::details
to disambiguate.

If there are names in common and one tries to use such a name,
then there will be an ambiguity which must be resolved.  The
difference is that the names will be in different namespaces and
can be disambiguated, whereas two libraries that put the same
name into boost::detail simply cannot coexist.

> It seems more unlikely that other libraries use ratios_detail
> as namespace, isn't it?

That is just as unlikely as two libraries using
boost::ratios::detail.

> I've seen that a lot of libraries uses detail namespace and
> others lib_detail. I think that I will move all my uses of
> detail to lib_detail.

If all new libraries use lib_detail rather than detail, the
problem just shifts, unless you mean <lib>_detail, where "<lib>"
is replaced by the library name.  Still, as I've shown, that
simply mixes paradigms making it a little more surprising, I
should think.  If we can establish that pattern as desirable,
then new libraries can adopt it and it will be expected, of
course.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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